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Multi-scale correlations between topography and vegetation in a hillside catchment of Honduras / A. Nelson in International journal of geographical information science IJGIS, vol 21 n° 1-2 (january 2007)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 21 n° 1-2 (january 2007) . - pp 145 - 174 Titre : Multi-scale correlations between topography and vegetation in a hillside catchment of Honduras Type de document : Article/Communication Auteurs : A. Nelson, Auteur ; T. Oberthur, Auteur ; S. Cook, Auteur Année de publication : 2007 Article en page(s) : pp 145 - 174 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] analyse multiéchelle [Termes IGN] appariement d'images [Termes IGN] déboisement [Termes IGN] dégradation de l'environnement [Termes IGN] données topographiques [Termes IGN] flore locale [Termes IGN] Honduras [Termes IGN] indice de végétation [Termes IGN] modèle conceptuel de données localisées [Termes IGN] utilisation du sol Résumé : (Auteur) All systems have causes and effects that can be appreciated at different spatial scales. Understanding and representing the complexity of multi-scale patterns in maps and spatial models are key research objectives. We describe the use of three types of correlation analyses: (1) a standard Pearson correlation coefficient, (2) a ‘global’ multi-scale correlation, and (3) local geographically weighted correlation. These methods were applied to topographic and vegetation indices in a small catchment in Honduras that is representative of the country's hillsides agro-ecosystem which suffers from severe environmental degradation due to land-use decisions that lead to deforestation, overgrazing, and unsustainable agricultural. If the geographical scale at which topography matters for land-use allocation can be determined, then integration of knowledge systems can be focused. Our preliminary results show that: (1) single-scale correlations do not adequately represent the relationship between NDVI and topographic indices; (2) peaks in the global multi-scale correlations in agricultural areas coincided with the median farm size, but there was no evidence of any community or larger-scale land-use planning or optimization; and (3) local multi-scale correlations varied considerably from the global results at all scales, and these variations have a strong spatial structure which may indicate local optimization of land use. Copyright Taylor & Francis Numéro de notice : A2007-030 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/13658810600852263 En ligne : https://doi.org/10.1080/13658810600852263 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28396 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-07011	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-07012	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Using auxiliary information to adjust fuzzy membership functions for improved mapping of soil qualities / T. Oberthur in International journal of geographical information science IJGIS, vol 14 n° 5 (july 2000)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 14 n° 5 (july 2000) . - pp 431 - 454 Titre : Using auxiliary information to adjust fuzzy membership functions for improved mapping of soil qualities Type de document : Article/Communication Auteurs : T. Oberthur, Auteur ; A. Dobermann, Auteur ; M. Aylward, Auteur Année de publication : 2000 Article en page(s) : pp 431 - 454 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Cartographie numérique [Termes IGN] carte agricole [Termes IGN] carte pédologique [Termes IGN] classification dirigée [Termes IGN] logique binaire [Termes IGN] logique floue [Termes IGN] rizière [Termes IGN] sécheresse [Termes IGN] sous ensemble flou [Termes IGN] Thaïlande Résumé : (Auteur) Agronomic soil management and decision-making frequently requires the joint classification of soil variables. Fuzzy set theory is often used to accomplish this task. This paper addresses the issues of objectively defining fuzzy membership functions (FMF) and reducing classification uncertainty with hedge operators. As an example, soil in North-east Thailand was classified according to its inherent potential to support the recovery of a rice crop after a drought spell. The utility of auxiliary information not directly included in the classification was explored. A tree cover density index was employed for an objective definition of the FMF to classify soil organic matter content and plant-available potassium. Mapping units were allocated to classes having low, medium or high availability of these plant nutrients. It was shown that crisp, Boolean style classifications severely misclassify land in all but one class. Adjusted FMF decreased the uncertainty contained in thematic class maps. Single FMF values for soil organic matter and plant-available K were then jointly modelled and the soil classified as having low, medium and high potential for rice plants to recover from drought impacts. The very and more or less hedge operators were applied to increase or decrease the joint FMF values using farmer' knowledge about soil fertility. Overall classification uncertainty using FMF was decreased by 14% if the standard FMF was adjusted and the generated membership values were hedged. It was shown that adjusting FMF influenced the uncertainty components vagueness and ambiguity differently; the former increased slightly but the latter was drastically reduced. Numéro de notice : A2000-133 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658810050057588 En ligne : https://doi.org/10.1080/13658810050057588 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21549 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-00051	RAB	Revue	Centre de documentation	En réserve L003	Disponible